GPS Navigation Message

Jalbert — Mon, 01 Jun 2026 08:31:33 GMT

Small fix in LNAV sub-frames 4 and 5.

← Older revision		Revision as of 08:31, 1 June 2026
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	* Sub-frame 5: contains data from the almanac and the constellation status. It allows to quickly identify the satellite from which the signal comes. A total of 25 frames are needed to complete the almanac.		* Sub-frame 5: contains data from the almanac and the constellation status. It allows to quickly identify the satellite from which the signal comes. A total of 25 frames are needed to complete the almanac.
	Sub-frames 1, 2 and 3 are transmitted with each frame (i.e., they are repeated every 30 seconds). Sub-frames 4 and 5 contain different pages (25 pages each) of the navigation message (see figure 1). Thence, the transmission of the full navigation message takes 25 × 30 seconds = 12.5 minutes.		Sub-frames 1, 2 and 3 are transmitted with each frame (i.e., they are repeated every 30 seconds). Sub-frames 4 and 5 contain different pages (25 pages each) of the navigation message (see figure 1). Thence, the transmission of the full navigation message takes 25 × 30 seconds = 12.5 minutes.
	The content of sub-frames 4 and 5 ~~is common for all~~ satellites. ~~Thence~~, the ~~almanac~~ data ~~for all in orbit satellites~~ can ~~be obtained from a single tracked satellite~~.		The content of sub-frames 4 and 5 can be different between satellites. Furthermore, within the GPS LNAV navigation data structure, these subframes can differ depending on whether the PRN numbers belong to the lower set (1–32) or the upper set (33–63).

	Further information on the LNAV message can be found in IS-GPS-200 ICD document <ref name="GPS ICD 200">[https://archive.gps.gov/technical/icwg/IS-GPS-200N.pdf GPS ICD-200 Revision N, "Navstar GPS Space Segment/Navigation User Segment Interfaces"]</ref>.		Further information on the LNAV message can be found in IS-GPS-200 ICD document <ref name="GPS ICD 200">[https://archive.gps.gov/technical/icwg/IS-GPS-200N.pdf GPS ICD-200 Revision N, "Navstar GPS Space Segment/Navigation User Segment Interfaces"]</ref>.

BeiDou Signal Plan

Dgarcia — Fri, 29 May 2026 14:16:05 GMT

@@ Line 196: / Line 196: @@
 |-
 | Received Power Levels on Ground || -156 dBW for MEO and -158 dBW for IGSO satellites (measured at the output of a 0 dBi RHCP user receiving antenna when the satellites are above a 5-degree elevation angle)
 |-
 | Signal Multiplexing Mode || Code Division Multiple Access (CDMA)

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GPS Navigation Message

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